Heat treatment of articles of iron and steel and alloys thereof



W. M. MORDEY.

HEAT TREATMENT OF ARTICLES OF IRON AND STEEL AND ALLOYS THEREOF APPLICATION FILED JUNE 2. 1920'.

1,41 2,484, Patented Apr. n, 1922.

one; AVAILABLEQ QEJ UNITE STATES WILLLAM MORRIS MORIJEY, OF WESTMINSTER, ENGLAND.

HEAT TREATMENT 01* ARTICLES or 112.01? Am) STEEL AND ALLOYS THEREOF,

Application filed June 2, 1920. Serial No. 386,030.

1 '0 all whom it-mag concern:

Be it known that I, WILLIAM MORRIS MonDEY, a subject of the King of Great Britain and Ireland, residing at Westminster, England, have invented Improvements in or Relating to the Heat Treatment of Articles of Iron and Steel and Alloys Thereof, for which I filed an application in Great Britain May 8, 1918, No. 17,117 of 1919,) of which the following is-a specification. 7 In the specification of another application for Letters Patent filedby me, dated June 2nd, 1920, Serial Number 386,029, I have described the heat treatment of tram- Way and like rails formed of iron or steel or alloys thereof, either in situ after laying, or before laying, the object being to enable the heating of the rail to a high' temperature to be effected in a simple, quick andconvenient manner so that the physical conditionof the rail can be altered and improved, and particularly for enabling a rail made of suitable steel to be heated to a sufiiciently high temperature to admit of its being subsequently hardened and toughened by suitably cooling it.

Now the present invention has reference to improvements in the heat treatment'of articles of iron and steel and alloys thereof, of various kinds, other than rails, as for example plates, sheets, cylinders, shells, rods and other articles for the purpose of enabling special qualities or characteristics to be imparted thereto or to parts thereof.

For this purpose, such an article, which is hereinafter called. a steel article, to distinguish it from atramway or like rail (hereinafter called a rail) forming the subject of my said other application for patent, is heated by arranging it in the magnetic circuit of an alternate current electro-magnet which may be one phase or multiphase and is so constructed that an alternating magnetic flux will be induced in the steel article under treatment of'sufiicient value to'set up eddy currents therein of such strength, aided to some extent by magnetic hysteresis, as to heat the steel article to the temperature required but not to a temperature exceeding the critical non-magnetic temperature of the particular steel of which the article is composed, use being made for this purpose of the fact that the generation of heat .will then automatically cease to increase owing to the permeability of the heated steel article being then considerably reduced. After being thus heated to the desired temperature, the article 15 suitably cooled to impart thereto the desired characteristics.

In or associated with the winding of the electro'magnet is placed an indicating instrument which may be an ammeter, or a voltmeter, or a wattmeter, or a power factor meter, to show when the heating" of the article has reached the required temperature, Which Will vary-more or less with different kinds of steel. An infallible indication of the desired temperature having been attained, will be given by the instrument, whlch will respond to the altered condition of the magnetic circuit.

In the accompanying'illustrative drawings, F igs. 1 and 2 show respectively in side and end elevation and more or '-less diagrammatically, onewayof carrying out the invention. Fig.3 is a vertical section on the line III- III of F ig. 1 and Fig. 4: a horizontal section on the line IV-IV of Fig. 3, showing a modified arrangement. Fig. 5 shows in side elevation a further modified arrangement. 1

The invention can advantageously be applied to the heating and hardening of articles of steel of various kinds, particularly tools, gauges and other appliances made of tool steel. For this latter purpose, there is used, as shown in Figs. 1 and 2, a powerful alternate current electro-magnet 7' having poles 7 which may vary in form and be interchangeable to suit various requirements. a is a switch for controlling the supply of alternate current to the electro-magnet. q is an instrument of one of the kinds hereinbefore described, for indicating when the article has reached the required temperature. In such an arrangement, the electro-magnet may, as in the example shown, be supported in any convenient way with a space below its poles. The article m to be hardened is, in this example, placed against the poles where it is held by magnetic attraction. The excitation of the electro-magnet is such that the article Will be heated, as liereinbefore described, by eddy currents due to the magnetic flux traversing it, and, tea certain extent, by magnetic hysteresis. When the article attains the critical non-magnetic temperature, it may be allowed to fall oif and may be allowed at once to drop into a suitable quenching bath 0 to harden it. To heat only one end portion of a tool or other article to the critical non-magnetic'tempera- Specification of Letters-Patent. Pate t d A 1 1922 see: AVAELABLE CQP ture, the electro-magnet may be applied to that end portion only, such end portion on becoming non-magnetic being released and, it maybe, allowed to fall off as above stated. The other end portion of the article can be kept sufficiently cool in any desired way, as by exposure to the air, during the heating of the opposite end portion.

To conserve heat and to prevent or diminish oxidation, the steel article may be surrounded or partly surrounded by a shield m (Fig. 2) of heat insulating material, as for instance asbestos. Or part of the poles f of the electro-magnet f and the steel article m to be heated, may, as shown in Figs. 1 and 2, be enclosed in a vessel p from which the airis exhausted, or in which an inert or reducing atmosphere is maintained. The article m may also in this case and as shown in Fig. 2, be provided with a shield m.

Figs. 3 and 4 show how the invention may be applied to the heat treatment of hollow iron and steel articles, such as shells or cylinders, the article shown in the example being an armour piercing shell 1-. In this case the electro-magnet f, built up of laminated iron sheets, is made of tubular shape with multiple poles 7 arranged to surround and conform more or less to the shape of the shell and energized by windings 7, the electromagnet being arranged to be placed over the shell or the shell to be inserted in the electromagnet. The two may be separated from each other by means, such for instance as lengths s of asbestos.

In the heat treatment of iron and steel and alloys thereof, such for example, as plates, sheets, rods and the like, but excepting tramway and other rails, the article and the alternate current electro-magnet may, when necessary, as for instance owing to the length of the article, be moved endways relatively to one another so as to heat successive ortions of the articles along its length.

hus, in Fig. 5, f is a stationary alternate current electro-magnet of the kind referred to, and u an elongated article of one or other of the kinds referred to, for instance a plate, that is movable endways below the poles f of the electro-magnet. The article 11. after being heated as described tothe desired temperature, is rapidly cooled, as by water, or

an air blast, issuing from a nozzle 41 to impart thereto desired characteristics.

Or the heating of the steel article 1(- may be etfected partly by electro-magnetic means as described. so as to preheat it to any desired temperature up to the critical nonmagnetic temperature, and partly by supplementary heating means, such for example as a suitable flame to (see Fig. 5) extending from a nozzle :0, so that the temperature of the article can be raised to the critical nonmagnetic temperature, or, if desired even to a higher temperature. The flame nozzle m.

when used, will be arranged near to the magnet poles and be succeeded closely by tilt mainly produced at and near the surface 0' the article. The frequency may be varied as one means of controlling the depth or penetration of the heat in the article.

Cooling arrangements are or may be pro vided to prevent overheating of the poles or other parts of the electro-magnet as for ex ample by arranging the poles f to extend ll a water tight manner, through a box 1 (Fig 5) through which, and inlet and outlet pipe: y, 1 water is caused -to flow. Also, mean; may be provided to minimize heating of th poles of the electro-magnet by heat derive( from the article, or portion thereof, for thl time being under treatment. For this pur pose, non-conducting material for instanc lengths of asbestos s (Fig. 4) or sheet as bestos 1 (Fig. 5) may be arranged betweel the poles f and the article or articles being heated. The laminae of the poles are pref erably insulated with very thin mica.

lVhat I claim is 1. The heat treatment of an iron or stee article other than a rail for the purpose 0 altering and improving the physical con dition of the metal of which the article i composed, such treatment consisting in ar ranging the article in a magnetic field se up between the magnetic poles of a powerfu alternate current electro-magnet so that th article will form part of the magnetic cir cuit of the magnet core and will have in duced in it a magnetic flux and consequentl; eddy currents of such strength as thereb to become heated to the desired temperatur limited by the critical non-magnetic temper ature of the metal of which the article i composed, and afterwards cooling the sail article.

2. In the heat treatment of an iron or stee article, other than a rail, according to clair l, cooling the said article rapidly after i has been heated to the desired temperatun 3. In the heat treatment of an iron 0 steel article, other than a rail, accordingt claim 1, energizing the electromagnet b; alternate current of high frequency to limi the depth of heating of the article unde treatment. substantially as described.

4. For carrying out the method of hea treating an iron or steel article, other than rail, according to claim 1, apparatus com prising an alternate current electromagne having a core terminating in two adjacen magnetic poles spaced a art to form be tween them a magnetic eld in which th article to be treated is arranged and a winc" netic core and thereby generate heat in theportion of the article for the time being in the magnetic field between the said poles and forming part of the magnetic circuit, a current supply conductor for said winding and an indicating device associated with the said current supply conductor and adapted to show, in consequence of the altered condition of the magnetic circuit including the magnet core and portion of the article under treatment, when the heating of the said portion of the rail has reached the desired temperature.

5. For carrying. out the method of heat treating an iron or steel article, other than a rail, according to claim 1, apparatus comprising an alternate current electro-magnet having a core terminating in two adjacent magneticpoles spaced apart to form between them a magnetic field in which the article to be treated is arranged, a winding adapted to powerfully energize the magnetic core and thereby generate heat in the portion of the article. for the time being in the magnetic field between the said poles and forming part of the magnetic circult, and means for protecting the saidarticle from oxidation during the heating thereof.

6. For carrying out the method of heat treating an iron or steel article, other than a rail, according to claim 1, apparatus comprising an alternate current electromagnet ranged to be heated by the magnetic flux having a'core terminating in adjacent magnetic poles spaced apart to form between them a magnetic field, a steel article arpassing through said field and non-magnetic material covering said article whilst it is bein heated.

For carrying out the -method of heat treating an iron or steel article, other than a rail,- according to claim 1, apparatus comprising an alternate current electro-magnet having a core terminating in adjacent magnetic poles spaced apart to form between them a magnetic field in which the article to be heated is arranged so that it willforrn the purpose set forth.

9. The heat treatment of an article formed of tool steel,nfor the purpose of heating and hardening it, by applying the article. to the poles of an alternate current electro-mag net, energizing said electro-magnet and thereby heating the article by alternating magnetic flux caused to pass through it'and when heated to the critical non-magnetic temperature rapidly cooling it.

10. The heat treatment of an article formed of tool steel, for the purpose of heating and hardening it,- by applying the article to the poles of an alternate current electro-magnet, energizing said electro-magnet'and therebyheating the article by alternatin magnetic flux caused to pass through it an when heated to the critical non-magnetic temperature allowing the article auto matically to fall ofl of the poles of the elec: tro-magnet and into a cooiling medium.

,.1920. a j WILLIAM MORRIS MO-RDEY. U

SLiFned at London, England, this 17th day of a v j 

